Pulse testing equipment



IJan. 4, 1949. F. H. HIBBARD PULSE TESTING EQUIPMENT Filed June ,26, 1943 ysoio ATTORNEY Patented jan. 4, 1949 PULSE TESTING EQUIPMENT Frank H. Hibbard, Mountain Lakes, N. J., assigner to Bell Telephone Laboratories, Incorporated,

New York, N. Y., a corporation of New York Application June 26, 1943, serial No. 492,472

This invention relates to testing equipment and has for its object to provide a very rapid, accurate indicating means for use with such equipment.

In designing a vdevice for generating pulses, such as a dial for use in a commercial circuit, it is necessary to` determine the maximum and minimum values of the individaul pulse make and break whichthe device will produce under all variations of manufacture and use. Hence it is essential to the design of pulse generating devices and circuits to provide convenient means for testing individua] pulse time values.

One well-known method for observing the make-and-break operations of a pulsing device is by the use of an oscillograph, but this method is not suitable for adjustment and maintenance because` of the quantity of paper tape required and the time and labor of making readings from the tape.

A classic method of measuring the'length of a circuit closure is by the charge produced on a condenser during such closure. 'Howeven the known methods of measuring or reading the condenser charge by the observation of ballistic galvanometer displacement, or by balancing the condenser charge voltage against a potentiometer voltage are not suciently rapid for the successive reading of individual pulses in a train of ten pulses occurring within a time of approximately one second, such as are used in commercial circuits.

In the present invention means is provided for indicating instantaneouslyy the occurrence of preset maximum or minimum values of condenser charge resulting from circuit closure, rapid enough so that a single condenser can be read to limits, discharged, and presented to the pulse generating device in time for testing the next succeeding closure. By the usual methods of relay switching a second condenser may be similarly charged, read, and restored, to test for the open-circuit time values lof successive pulses of the generating device. Thus the individual pulse values of make and break are continuously tested within maximum and minimum limits.`

These advantages are obtainedby the concurrent method of measuring the charge voltage of the condenser disclosed in the invention. In the previously` known methods of determining condenser charge voltage corresponding to circuit closure time, the'measurement of condenser voltage remaining as a stored charge takes place after the time interval has elapsed and the circuit opened.` In the present invention, the final Charge of a condenser is determined by connect- Claims. (Cl. 179-1752) ing in series with thecondenser the actuating vcoils of a low-inertia device such as an electron of the condenser charge voltage, and hence ofY previously elapsed time of charge. Hence the underlying idea of this invention is the direct conversion of condenser charging current into physical displacement by electromagnetic means. An advantage of this invention in continuous testing is that the condenser voltage is already converted to a physical displacement which can be evaluated immediatelyl and the speed of reading is greatly incre'asedover the galvanometer or balance methods which require conversion of condenser charging` current into physical displacement by electromagnetic means. A further advantage of this invention is that the same circuit which charges the condenser also actuates the indicator, thus reducing switching operations and the uncertainties of mechanical electrical contacts in the reading of quantitative values. Another advantage of this invention is that the condenser is not required to store a charge for any period after the charging circuit is open, and the resultsare less directly affected by condenser leakage.

More specically, the circuits including the two beam-displacing coils of the electron tube are so tuned that the out-of-phase currents generated therein by the closure of the charging circuit cause the electron beam to rotate through an angle which is a measure of the time of the closure.

A series of electrodes are mounted in the rotating path of the electron beam and certain of these electrodes are connected to other gas-filled tubes so that as the electron beam strikes an electrode the associated tube Abecomes conducting. Preferably four tubes would be employed, viz., one attached at a point reached by the beam immediately following the start of the pulse closure, one

attached at a point just ahead of that reached by the beam in response to the minimum acceptable closure, one at a point just beyond that reached by the beam in response to the maximum acceptable closure and the fourth at an intermediate point. Means is provided operable in the open-circuit interval of the pulse to determine which gas-filled tubes havebeen operated and to discharge them.

By the use of a second rotating beam tube and spouse to a long pulse. These elements are marked 2 to indicate that they function second. After an additional interval the element 49 (marked 3) opens its contact. All of the contact elements are arranged to return to normal quickly, as described in the above-identified Pollard patent.

The closure of contact 44 supplies battery to the anodes of tubes 2t to 35. Contact 48 controls a quick-acting counting mechanism 4i to count every pulse which operates relay 40. The opening of contact da quenches tube 2l and releases relay 4d, to make it ready-for the next pulse.

It 'would be possible to observe tubes 21 to 30 visually to note which tubes ash in response to individual pulses but for a continuous test some means of registering is required. For this purpose tubes 132 and i3 are provided.

Relay i0 by means of its contact 45 supplies operating potential to the tubes 42 and 43 through the windings of counting devices 52 and 53.` At contact element 4S of relay 40 the control anode of tube 43 is momentarily connected to a point between resistances 35 and 36 which are in turn connected respectively to the anodes of tubes 28 and 29.

The circuits of tubes 28 and 29 are arranged in the form of a Wheatstone bridge, with the tubes in two arms, resistances 3l and 59 in the other two arms and resistances 35 and 36 in the bridge. If only tube 28 is discharging the bridge will be unbalanced and the current flow through resistances 35 and 36 is sufficient to overcome the bias applied to the control anode and to discharge tube 43. With tube 43 conducting a circuitis completed for counter 53 to indicate a short pulse.

II both tubes 28 and 29 are discharging, the bridge is substantially balanced and no current flows through resistances 35 and 36, whereby the potential applied to the tube 43 is insufhcient to overcome the bias applied to the control anode of tube 43 and counter 53 is not operated. Therefore for any pulse of at least satisfactory length, no registration is made on coun-ter 53.

Similarly contact element All connects the control anode of tube 42 to the anode of tube 30 so that if tube 3E is discharging tube 42 will break down and operate counter 52 to indicate a long pulse. It will be apparent, therefore, that counter 4l counts all pulses received, counter 53 counts all pulses which are shorter than the standard set up and counter 52 counts all pulses which are longer than that standard.

Counters 52 and 53, which may be of the type used for metering telephone calls, control auxiliary contacts which, when either counter has fully operated, connect ground to the associated tube to quench it and release the counter. It is obvious that any convenient type or" counting mechanism might be employed. Y

The circuit of Fig. 4 may be employed to test the length of the open period of the pulsing Contact l by reversing the connections to the back and front contacts of contact i.

One source of the speed oi this method of measuring pulses lies in the fact that the electric circuit ywhose current-time characteristics are used for the time measurement or clock is electrcally quite divorced from the means used to read the clock. The magnitude of electron iiow in the gas-filled tubes'used to indicate the length of the pulse is not controlled by the measuring circuit; a normally constant flow of safe magnitude is previously set up and maintained. The magnetic field resulting from the current ow in the measuring circuit displaces the electron stream, with the displacement instantaneously controlled by measuring circuit currents, which are in turn proportional to elapsed time. By taking a signal from an electrOde which the rotating beam contacts at a predetermined displacement, a quickly made limit reading is made, that is, a record that the elapsed time has equalled or exceeded the known time which it takes the beam to reach the displacement under the control of the measuring circuit.

Thus, this method of reading the instantaneous current, and hence time, in a condenser-resistance-inductance network by the displacement of an electronic beam electrically external to that circuit has three unique characteristics, viz.,

That the measuring circuit is made up of elements having highly stable, dependable and controllable values of capacity, resistance and inductance and is independent of interconnection with the circuit required for recording.

That the change of current in the measuring circuit is observed by displacement of the focussed electron beam in a vacuum tube by magnetic coupling, whereby the record is not dependent on quantitative ow or change of flow of electrons, but only on the magnetic coupling and the inertia characteristic of the beam.

That the record is already prepared and instantly recorded when the measured time is completed.

Fig. 5 shows an alternative means of recording the speed of a pulsing contact by the use of a high speed motion picture camera which simultaneously photographs the tube Si together with the path of the beam 62 and the pulsing contact 63. This arrangement would be particularly valuable in observing pulses to an exact value of time rather than to acceptable limits.

What is claimed is:

1. Testing means for measuring the duration of pulses comprising a condenser, an electron beam tube having a pair of coils for rotating the electron beam, a circuit for simultaneously charging said condenser and energizing said Icoils in accordance with the charge received by said condenser in response to each pulse to produce a displacement of said beam proportional t0 the duration of each pulse, and means responsive to said beam during said displacement to register the extent of said displacement.

2. Pulse testing means comprising electron discharge apparatus having eld magnets for generating a rotating electron beam, a circuit for generating a two-phase transient current in said eld magnets in response to each pulse, and means operated in accordance with the rotation of said electron beam in response to said transient current to indicate the relative length of said pulses.

3. Testing means for measuring the duration of pulses comprising an electron beam tube, means for displacing the beam of said tube in accordance with the duration of each pulse, a plurality of anodes for said tube mounted in the path of said beam, said anodes so located as to mark the displacement of said beam produced by short pulses, satisfactory pulses and long pulses, respectively, a gas-lled tube connected to each of said anodes indicating the duration of pulses, registering means including a iirst means for counting the number of operations of said long pulse indicating tube, a second means for count,

thfef satisfactory puise indigating ,tubef t' rende'r said second counting means ineffective.

fi. Testing means ior measuriv thewduration' of pulses comprising an' ctron b i'mf msaiisl for displacing thehs m Qf said tiib accordancewith Atl`1e du `rat of' ch' plurality of anodesfor s aidtub' m I Path of saldi transmitan sessel 1. mark the displacement;dfsaidbeam short pulses, satisfactor;7 p lses anddonjs'p respectively, af gas-filled" tulc'e connected toje h of said aiiofies iiidisatiiistiis, c iiiiiitieii,Qi` ii registering means and'means "f or cpp'eQ/ll, registering means tof saidv indicating t b'sj b tweenpulses, said registeri gUmeansjincludi first cuntin'g means forr counting: lofiigp es' by counting the number of operations ofsaifdf long pulse indicating tube, and a' second counting@ means for counting short pulses, said" se'c counting means so associated with saidshort' pulseindicating tube and saidsati'sfactdryp lse indicating tube that said secoi'idsiiiitiiisiil. is rendered unresponslve'if said satisfactory pulse indicating tube is operated;

5. Testing means for measuringthe dA ofV pulses comprising an*A electronl beam" tube; means for displacing the beam of said tub accordance with the duratirm of eachpul's' setof four ande'sfor said tube'mourit'ed path of said beam, one o f said anodes being: s located as to be in the path o f any dslilieiiefll of said beam, a second anode so located as to mark thedisplacement produced byapulseof less than the minimum allowablejduratioii* awtnir'd; anodefso located as to'mark'thedisplacement; produced by a pulse of satisfactory duration and the fourth anode so located `as to niark liliedisr placement produced by a pulse; of inprie thanthe meilliliim allowable. deiatisiit eas-filled tubes connected to said anodes and operative in riespo'nseto theA irnpngement o f said beam' ori the" assoc'iated anodetoindicate lthe duration; of; ai? puls,4 registeringI means, andumeans controlled' by. the' sas-filled tiibe .dissected to' said. first anode to connect said registering meanstothe other gaslled tubes to register pulses of unL satisfactoryv duration.

6. Testing means for measurllg'jhe duration 0f pulses Colllitllsllls election beam, tulsa" msaiisfoi' displacing the beam Q-issici tube in accordance with the duration j each pulse,a s et of four anodesior said tube mountednin thepatn 55 of `said beam, oneV of said `anode`sf be i ng s p located, as te be in the pathfofany dispiacere@ 9g saigij beam, a second anode solocatedasfto mayrkwtliey displassmsiit Ditoducedfbyi'aiiiilss O'flsss thea iiiiriimimiallG-Wabis ,Cliiiatiri'v ai tiifiii ai'iclss 6o located asto m ark the' displacement produced apiilse 0f satisfactory duration and tlieqiirth anode so located astmark tliel displacement` PiQdi'il-i by ,s'eiils'fii msretiiaii allowable duration, gasfiilled'tiibesconnected to 65 said anodes and'operativefinlrespo e toftheirn pingement of said beard o'nfth'e as spciated antigen t9 'ii'idiate' the" duration' @fj a [iiliil`s`lk .is I iliig means, 'arelay operative under thwoit' l Yoftlfef.y gas-filled 'tube' connected tolsaidjiir'st a n relayf effective in the bv eenpizilsfsltdgasllled tubes"y to rfegisteif pulses 051 saliti; 7o

connect Saidfreistenngnra wit Athe' other sued tubes 75 of?, cui@ anodesfpr said tube mounted in the npath immuni allowable duation, a third anode solocatledfasto marl'f the displacement prximzed- Die Pillsifsatisi'toir diiiatiori and the'foiirtii anode so locatedas tyinarkVy the displacement d by `aliiilse off rnor e than the maximum allewablfi'. fiiiratirileas-iillsd tiibessoniiested `to saidlanodes 4and operative in response 4to the img pingement of said beamen the associated anode te.,.lililletev.tli .,Clliiatliiri @if a pulsa registering a relay operative under -the contrplof the itiiiislsiiriesisd to saidiirlsi. anode, said sas,-

relay successiyely effective to prepare said duration indicating gasfllled tubesior operation, for

@Ollfltililasald ..igisteririg^ means t0 said eas-` lledtubes after the termination of a pulse and to restore all of said tubes.

8,jTesting means for measuring the .duration of.a ,.S 1ies of pulses'comprising acondenser, an electron'beam tube having a pair of coils for rotatingV the electron beam, a'circuit ffor simultaneously' charging said'c'onden'ser' and energizing` said coils in accordance with the charge received by said condenser' in response' to' each pulse to produce a displacement ofsaidbea'm 'proportional to' the 'duration 'o'feacl' pulse; means responsive to said beam during'rsad' displacement to indicate' the" extent' of'V said" displacement, and means oprativebetweeri pui-sesto register said indi'- "eans "comprising a4 condenser,

9. Puisitestng rotatinghelection'b'eam, a' circuit for generating' a two-phase'translentcurrent in said field magnetsin'aceordarce'witli'the charge on saidcon'- denser to' rotatesaid beam, and 'means operated in"accordance`with tlie'exterlt of the rotation of said'"electrori*beamA in'response to' said transient' current'to indicate the relative length of said pulse;

10.' i Testing" means" for measuring the duration of each of a series of pulses comprising a con` danser-,1 means fm;av chargingfsaid' condenser@ resplnse'to'eah of'said'pulses, anelectron beam tubefhaiingfildimaginets for generating a rotating elejltrbri"Y 'riiearis':f or"` rotating the bant of"sai`d"tube"in accordance Withjthecharge on said condenser; aplurality of anodesfor'said'tube mounted iii .tlisieth Oisald beam, saltiv allseits s0 located as to"ma r l 'the' rotation of said beam by ti' s pulses l of satisfactory duration and' by pulses of mcrethan a in a irnum allowable dura# tisafresiisciiveiy, spiiiislinyf siennes tubes M ted'Withsaid;'an9des"and' operatV in rea spense t irripinjgeriilentof said beam on the,

associated nodefarid means under the control'of said j vtubes tof register the number of pulses'ofunsati'sfactoy' duration.

(efeiences on following page)v pulses effle's'sctiiaiitlie iiillllmiiin Yalliliwfilile dura-,

REFERENCES CITED UNITED STATES PATENTS Date Name Haig Dec. 31, 1907 Goodrum Sept. 5, 1916 Booth Nov. 61928 Kunze May 20,` 1930 Massonneau Mar. 10,1931 Ulrey Aug. 9, 1932 Pitt Nov. 21," 1933 Sabbah et al Sept. 24, 1935 Number Number Name Date Dmond July 13, 1937 Byrnes Oct. 5, 1937 Smith Jan. 10, 1939 Greentree Nov. 28, 1939 Pakala Jam 9, 1940 Ross Feb. 25, 1941 Wiley Jan. 13, 1942 Schweitzer Feb. 15, 1944 Brauer et a1 Nov. 26, 1946 Kessler et al Feb. 18, 1947 FOREIGN PATENTS Country Date Sweden Aug. 11, 1936 

